Oto-acoustic emission analyser

ABSTRACT

A hand-held, battery-driven, oto-acoustic emission analyzer comprises an apparatus housing with two areas; an elongated housing part for electronic circuits, a measuring probe and a display, and a handgrip part for containing a power supply unit in the form of a battery compartment and a pump, such as a mechanical, hand-operated pump.

BACKGROUND OF THE INVENTION

The invention relates to an oto-acoustic emission analyser.

Such an apparatus is used for audiometric emission measurements on anindividual, e.g. a person whose hearing ability is to be examined.Emission-like measurements are discussed for the first time in Danishpatent no. 147,726 (U.S. Pat. No. 4,374,526), in which the Britishresearcher D. T. Kemp deals with the measurement of echo signals from aperson's inner ear, i.e. measuring of an acoustic echo brought about byintroducing an acoustic signal in the form of a transient audio signalinto the ear by means of a transducer. This measuring technique hassince been further developed, and it has now become apparent that whatis involved is not an echo but a stimulated emission from the inner ear.It has subsequently been ascertained that the emission can be stimulatedin other ways, e.g. by using tone pairs, so-called stimulus signals,which consist of two or more pairs of substantially sinusoidaloscillations, these pairs having frequencies which lie relatively closeto each another, e.g. so that one signal has a frequency in the range of1.2 times the other frequency. This technique is described, for example,in international application no. WO 93/20746. Others have developedother signal combinations which can also stimulate the inner ear toprovide measurable emission signals.

As a minimum, an emission measurement thus requires a measuring probe tobe introduced into the ear of the person on whom the measurement is tobe carried out, said probe comprising at least one, or preferably two,transducers for the generation of stimulus signals, and at least onetransducer for measurement of the emission signal, plus an associatedelectronic circuit, partly for the generation of the signals and partlyfor the processing of the emission signals. Equipment of this kind hashitherto been produced as table-type apparatus of a certain size, towhich a long cable is connected. One end of the cable is connected tothe table apparatus, and the other end of the cable is connected to aprobe unit with a measuring probe. For example, such an apparatus isdepicted and explained in Danish patent application no. 393/93, which isowned by the applicant of the present application. Such table-typeequipment can carry out the desired measurements, but it is requiredthat the person or the individual to be measured is brought to theequipment, which can often be inexpedient. It is particularlyinexpedient if systematic measurements, so-called screening, are to becarried out on a certain group of the population, e.g. new-born babies.Table-type equipment with cable and measuring probe also often suffersthe disadvantage that a calibration is required if the probe isreplaced.

Other types of audiometric apparatus are known for the screening of apopulation group, where the apparatus is portable, e.g. carried in thehand. A hand-held tympanometer, i.e. an apparatus for measuring theacoustic impedance in the outer ear under varying pressure conditions,is known from U.S. Pat. No. 4,688,582. However, such an apparatusprovides only limited information concerning the person's possiblehearing ailment. Consequently, there is a need for an apparatus whichcan carry out more detailed measurements and thereby provide aconsiderably better sceening result.

SUMMARY OF THE INVENTION

The apparatus according to the invention, has the advantage that it iscompletely portable, so that it is possible, e.g. at a hospital, in aschool or similar institution, to quickly carry out a screening forhearing ailments by an oto-acoustic emission measurement on eachindividual. The apparatus according to the invention, since it does nottake up much room or weigh very much, can also form part of theequipment carried by health care personnel or by practising doctors, sothat these people while on their rounds or sick calls or other visits tothe home, e.g. in connection with a birth or the like, can more easilyundertake a routine examination or possibly make a diagnosis. Especiallyin the examination of children or other people with whom it is difficultor impossible to communicate, the apparatus according to the inventionis a very great help in making diagnoses of impairments of those organswhich form part of the hearing.

The apparatus according to the invention may be configured with areplaceable tip for reasons of hygiene, without it being necessary tocalibrate the apparatus after the replacement.

By configuring the apparatus with a pump connected via an air hose tothe measuring probe, the pump can be used to carry out a so-calledmiddle-ear compensation. If the eardrum is distended in an arc, i.e. dueto an overpressure or an underpressure in the middle ear, this can becompensated for by applying a corresponding pressure or underpressure inthe area of the ear canal which is blocked by means of the probe tip.Compensation is hereby made for the changed flexibility of the eardrumdue to the pressure or the overpressure, while the result that theemission measurement can still be used. Placing of the pump in thehandgrip gives the apparatus good balance with regard to weight.

The pump can be electrically-driven or hand-operated. Where the pump ishand-operated, the cost of the apparatus and its power consumption andweight can be reduced, which is extremely desirable. For example, thepump can consist of a rubber ball or bellows or the like, and withcorresponding over- and underpressure valves.

The apparatus according to the invention may be configured with abattery and power supply in a handgrip, so that the resulting apparatuslies good and stable in the hand. The handgrip is particularly suitablefor housing the pump and the battery, so that from the weight point ofview the apparatus is well-balanced and herewith easy to use withoutcausing any unnecessary discomfort to the person being examined. Thebattery can either be of the re-chargeable type, or ordinary,replaceable batteries can be used.

The apparatus according to the invention can be configured so that thetip of the probe comprises a seal against the ear canal, said seal beingmade of soft, deformable material so that a good seal is achievedwithout causing the person being examined any unnecessary discomfort.

In another embodiment, the apparatus according to the invention isconfigured with the probe at one end of an elongated part and thedisplay at the other end. The apparatus thus achieved is easy andlogical in use, is well-balanced and is simple and quick to adjust andto use.

The apparatus according to the invention can also be configured forcommunication of information with other apparatus. For example, theapparatus can be arranged in a manner which allows the data collected inthe apparatus to be transferred to other apparatus, and possibly suchthat the apparatus can be simultaneously supplied with current for thecharging of the battery. The transfer of data can be carried out via aplug connection, but can also be effected by transmission, e.g. by meansof radio waves, sound waves or in another commonly-known manner.

BRIEF DESCRIPTION OF THE FIGURES

An example embodiment according to the invention is shown in the drawingand is described in more detail in the following, in that

FIG. 1 shows the apparatus as a whole seen from the side, substantiallyin full size, and where parts of the apparatus are shown transparent,

FIG. 2 shows the apparatus in FIG. 1 seen towards that side in which thedisplay is disposed,

FIG. 3 shows the apparatus in FIG. 1 seen from the front in towards themeasuring probe,

FIG. 4 shows the apparatus in FIG. 1 seen from underneath, and

FIG. 5 shows a complete, electronic block diagram of the electrical andelectronic circuits for the apparatus.

DESCRIPTION OF THE EXAMPLE EMBODIMENT

FIGS. 1-4 of the drawing show an oto-acoustic emission analyser 1according to the invention built completely into an apparatus housingconsisting of two housing parts, i.e. the handgrip part 7 and anelongated housing part 6 integral herewith. The housing part 6 ispointed or arrow-shaped towards that end at which the measuring probe 2is mounted, see FIGS. 1-4. The measuring probe 2 comprises a probehousing 4 which is surrounded by a union which secures the replaceableprobe tip 3, e.g. configured as shown and explained in the applicant'searlier Danish patent application no. 393/93. The housing part 6 alsocomprises a display 5, e.g. an LCD display, and a keypad or a number ofoperating keys 15 disposed on that side which faces towards the personwho operates the apparatus. The display 5 is mounted on a printedcircuit 16 which constitutes a display control circuit inside thehousing part 6, which in addition houses two or more prints 13, 14respectively with the input/output circuits 13 for the transducers, andwhich are explained later with reference to FIG. 5, plus adata-processing print 14 which is similarly explained later withreference to FIG. 5. Signal leads 11, 12 extend from the two prints 13,14 to the transducers 33, 34, 35 disposed inside the measuring probe 2and as shown and explained in connection with FIG. 5. Moreover, thehousing part 6 can also contain other electrical or electronic circuitsand components which are explained later with reference to FIG. 5.

The handgrip part 7 comprises two areas, i.e. an area 9 for a pump withassociated valves, e.g. a manual pump, and an area 8 arranged a batterycompartment, e.g. for a rechargeable battery or an ordinary battery. Oneside of the handgrip 7 is configured with ribs or the like which providea good grip, and possibly in such a manner that a pump in the handgripcan be influenced by a hand around the handgrip, said pump being, forexample, a rubber ball or bellows or a tube that can be deformed whenthe handgrip is squeezed. The part area 9 for the pump also houses thenecessary overpressure and underpressure valves which, via the tube 10,lead to the probe tip 3 from the pump, e.g. in a manner corresponding tothat explained in the applicant's earlier Danish patent application no.393/93. The valves ensure that a pressure which is too high or too lowcannot inadvertently be applied and thus irritate or injure a person whois to be examined.

Plug connections or the like can be provided in the bottom surface 17'of the free end of the handgrip 7, so that the apparatus according tothe invention can be connected to a charging unit for the charging ofre-chargeable batteries. There can also be means which enable theapparatus to be in data communication with other apparatus to whichstored measurement information and the like is to be transferred. Thesemeans can simply be a plug connection, but other means can also be used,e.g. if the communication is effected by means of radio waves, soundwaves or in another known manner.

The function of the apparatus will now be described with reference toFIG. 5 of the drawing, which shows a complete block diagram of theapparatus. For the sake of clarity, the same reference numbers are usedfor those parts or circuits in FIG. 5 which correspond to parts shown inFIGS. 14-.

In the upper right-hand corner of FIG. 5 there is shown a block 15 whichsymbolizes a keypad or a number of operating keys. When the apparatus isswitched on and set for measuring, an emission measurement is carriedout by introducing the probe tip into the ear canal of the person to beexamined, and activation of one of the keys 15. Possibly at the sametime herewith, the pump 9 is used to effect a change in pressure in theblocked area of the ear canal between the eardrum and the probe 2. Viathe keypad 15 there is selected a measuring sequence which is executedby the signal processor circuit 14, which comprises a digitalmicroprocessor, in that signals from here are sent to the controlcircuit 25 for the input/output circuit 13.

From here, the transducers 33, 34 are activated via the digital/analogueconverters 23, 24, in that the levels are regulated via the attenuators26, 28 and the output amplifiers 27, 29, and the stimulus signal isapplied to the person being examined via the transducers 33, 34. Thestimulus signal can be a sequence of tone pairs, a transient signal orother signal combinations as discussed earlier. The acoustic emissionfrom the inner ear is scanned with a measuring transducer (microphone)35, from where the signal is fed via a pre-amplifier 30, which cancomprise suitable filter circuits, further via a ranging amplifier 31 toan analogue/digital converter 22 to the control circuit 25 in theinput/output circuit 13. The signal, which is now in digital form, isfed from here to the signal processing circuit 14 where all thefiltering and data processing is effected, in that the signal processingcircuit 14 carries out the storage, the processing and the presentationof the signal values on the display, which is controlled via a displaycontrol circuit 16.

Via an interface circuit 17, which comprises the communication means 17'which are shown sketched in FIG. 4, signals stored in the signalprocessing circuit 14 can be sent to other units, e.g. stationary unitsfor further data processing, registration, printout etc. Moreover, dataor other signals can be fed into the microprocessor circuit 14 via theinterface circuit 17, e.g. concerning measuring frequencies or otherprogramming or control data for the signal processing circuit 14.

A suitable overpressure or underpressure can be established with thepump 9. The amount of pressure is regulated by the control unit 18 whichis controlled by the microprocessor circuit 14. The pressure isconducted to the measuring probe 2 via the tubes 10' and 10, and is fedforward to the blocked area between the probe and the eardrum, e.g. bythe probe being arranged as explained in the applicant's earlier Danishpatent application no. 393/93 or in another known manner. The actualpressure is scanned with a pressure-measuring transducer 19, from whichthe signal is fed via a signal amplifier 20 and an analogue/digitalconverter 21 to the control circuit 25 in the input/output circuit, andfrom here further to the microprocessor circuit 14.

The power supply unit 8, which comprises batteries and power supplycircuits for the individual electrical or electronic units, is not shownin further detail, in that this is configured in a commonly-knownmanner.

By feeding suitable sets of data into the microprocessor circuit 14, theoto-acoustic emission analyser according to the invention can be changedto be able to carry out other known measurements in connection withexaminations of the hearing ability, these measurements being based onthe application of sound to a person's ear canal, and possible scanningof the sound signals in the same place, e.g. while at the same timevarying or adjusting the pressure in the ear canal to a certain amount.

The parts 6,7, which together constitute the apparatus housing, can bemade of plastic, e.g by injection moulding in a commonly-known manner,or the housing can be made of an alloy. The housing can be configured asseveral parts which can be removed singly for the repair, servicing,adjustment etc. of the apparatus. If replaceable batteries are used, thepower supply unit 8 can comprise a battery cover.

The housing part 6, which narrows down towards the measuring probe 2, iscapable in the shown embodiment of housing substantially all of theelectronic circuits shown in FIG. 5, i.e. the printed circuit boards 13,14 and 16, as also shown in FIG. 1, and in the area between these boardsare placed the amplifiers 27, 29, 30, 31 and the attenuators 26, 28,e.g. in the form of one or more extra prints or flexprints.

In the shown embodiment, the handgrip part 7 forms an angle of approx.100°-120° to the housing part 6 and the longitudinal axis of themeasuring probe 2.

The measuring apparatus achieved with this configuration is balancedfrom the point of view of weight, and is thus easy to use withoutcausing the person to be examined any significant degree of discomfort.During a sequence of measurement, the apparatus is held with one hand,and the pump can be operated in a simple and convenient manner with thesame hand if this is necessary for the execution of the measurement.

I claim:
 1. Apparatus for measuring oto-acoustic emission from aperson's inner ear, comprising:a measuring probe having at least onesignal generator, and at least one signal receiver, the measuring probeadapted for introduction into the person's outer ear, an electroniccircuit for generating stimulus signals, including acoustic signals, andfor measuring and processing signals emitted by the person's inner earin response to a stimulus signal from the at least one signal generator,a display to display values of the signals, a power supply unit tosupply electrical power to the measuring probe, the electronic circuitand the display, and a housing to hold the measuring probe, theelectronic circuit, the display and the power supply unit, the housingbeing adapted to be held in a user's hand.
 2. Apparatus according toclaim 1, wherein the measuring probe comprises a replaceable tip thatincludes sound canals for the at least one signal generator and thesignal receiver.
 3. Apparatus according to claim 1, further comprising apump unit connected via a tube to the measuring probe to control airpressure in the measuring probe, the measuring probe comprising a probehousing, a probe tip a canal arranged for pressure communication betweenthe pump unit and a portion of the person's ear canal which is blockedby the measuring probe when the measuring probe is inserted in theperson's ear.
 4. Apparatus according to claim 3, wherein the pump unitis contained in a part of the housing which is configured as a handgrip.5. Apparatus according to claim 4, wherein the handgrip further containsthe power supply unit, and the power supply unit includes at least onebattery.
 6. Apparatus according to claim 3, wherein the pump unitcomprises a mechanical, hand-driven pump.
 7. Apparatus according toclaim 3, wherein the probe tip is arranged for mounting a soft,deformable seal for sealing against the person's ear canal.
 8. Apparatusaccording to claim 3, wherein the housing comprises an elongated partarranged to house the electronic circuit, with the measuring probemounted at a first end and the display provided on an end of theelongated part opposite the first end, and the housing comprises ahandgrip-part containing the power supply unit and the pump unit, thehandgrip-part extending from the elongated part.
 9. Apparatus accordingto claim 1, further comprising communication means connectable to otherapparatus for transferring data and information to and from theelectronic circuit.
 10. An apparatus for measuring an oto-acousticemission from a patient's inner ear, comprising:a measuring probeincluding an acoustic generator and an acoustic detector, introduceableinto the patient's ear; an electronic circuit to generate oto-acousticstimulus signals transmitted by the acoustic generator and for measuringand processing oto-acoustic emission signals received by the acousticdetector; a housing to hold the measuring probe and the electroniccircuit, the housing adapted for being held in a user's hand; a displaymounted on the housing to display data processed by the electroniccircuit; and a power supply mounted in the housing.